medicine, chemical, enamel, gunpowder, benefit
薬 centers on substances that alter or improve a state: medicine for healing, chemicals for effect, enamel as a coating, gunpowder as an explosive compound, and benefit as a positive outcome. The common thread is a transformative agent.
薬 is the modern simplified form of 藥. The older form combines 艹 (grass/plant) with 樂, which likely contributed the sound and the idea of something beneficial or enjoyable. The modern 楽 is a simplification of 樂.
Plants 艹 that bring comfort or joy 楽 are often used as medicine. Imagine gathering healing herbs that make you feel better.
For ヤク, picture a yak chewing medicinal herbs: yak -> ヤク, and the yak benefits from the plants.
medicine; pharmaceuticals; (legal) drugs; pill; ointment; salve
drug; medicine
narcotic; drug; dope
medical and pharmaceutical products; medicinal supplies; drugs; pharmaceuticals; medicine
pharmacy; drugstore; chemist's (shop)
ammunition; ammo
medicine manufacture; drug manufacture
medicine; drug
pharmacist; chemist
agricultural chemical; agrochemical; agrichemical
medicine; drug
gunpowder; powder
medicine; (pharmaceutical) drug; medical treatment
kettle
(study of) pharmacy; pharmaceutics
new medicine; new drug
explosive; blasting powder
eye drops; eyewash
administration; medication; dosage
Chinese herbal medicine
ring finger; third finger; fourth finger (esp. in piano-playing)
condiment (e.g. grated or chopped topping such as daikon, wasabi, ginger, green onion, red pepper); spice
reagent
specific medicine; wonder drug; silver bullet